2 1000-V Reference Voltage Source Characteristics

Ten 1000-V reference voltage sources were made. Before the PC boards are installed into the final device, each board goes through thermo training and thermo cycling for 120 hours, according to ISO 9000. The precision and stability of the voltage sources are regularly checked during 3.5 months using the HP3458A digital voltmeter.

The conclusions are:

1. Two hours are required to achieve the declared precision corridor of ±5 ppm.
2. 24 hours are required for the output voltage to stabilize in the precision corridor of ±2.5 ppm.
3. After stabilizing, the 24-hours change is within ±3 ppm. The most significant voltage difference between 10 devices after 48 hours is 7 ppm. The most significant voltage difference between devices after 72 hours is 3 ppm to 4 ppm.
4. The average voltage sources output value after 3.5 months is 1000.022 V.

Using the REF50xx two-terminal schemes allows building high-voltage reference sources for any voltage, including sources for tenths of kilovolts.

Currently, the voltage source for 100 kV is built using this method. 10000 REF5010 devices are used to build this device. This design probably hits the record of simultaneous use of TI parts in a single device. Its electrical parameters are under characterization.

Figure 2-1 shows the board that contains 500 serially connected REF5010 devices. The board is later cut into five 100-V strips to obtain better isolation. Together, these strips produce a 5-kV voltage stage.

A 100-kV reference voltage source is depicted in Figure 2-2.

NOTE: Full board view before being cut into 100-V strips.

Figure 2-1 100-kV Reference Voltage Using a REF5010 as the Base Element

NOTE: The boards are located inside the cylinder.

Figure 2-2 Common View of a 100-kV Reference Voltage Source